Multi-density model of the ionised gas in NGC 253 using radio recombination lines

We have imaged the H92α  (8.3 GHz), H75α  (15 GHz), and H166α (1.4 GHz) Radio Recombination Lines (RRLs) from NGC 253 at resolutions of 4.5 pc (0.4″) , 2.5 pc (0.2″) and 53 pc (4.5″) respectively. The H92α  line arises from individual compact sources, most of which possess radio continuum counterpar...

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Bibliographic Details
Published in:Astronomy and astrophysics (Berlin) 2005-03, Vol.432 (1), p.1-14
Main Authors: Mohan, Niruj R., Goss, W. M., Anantharamaiah, K. R.
Format: Article
Language:English
Subjects:
galaxies: individual: NGC 253
galaxies: ISM
galaxies: starburst
radio lines: galaxies
radio lines: ISM
Sciences of the Universe
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Summary:We have imaged the H92α  (8.3 GHz), H75α  (15 GHz), and H166α (1.4 GHz) Radio Recombination Lines (RRLs) from NGC 253 at resolutions of 4.5 pc (0.4″) , 2.5 pc (0.2″) and 53 pc (4.5″) respectively. The H92α  line arises from individual compact sources, most of which possess radio continuum counterparts. The line widths range from ~200 km s-1  for the sources near the radio nucleus to 70–100 km s-1  for the extranuclear ones. These lines are emitted by gas at a density ~104 cm-3. The remainder of the cm-wave RRLs arise in lower density gas (~500 cm-3) with a higher area filling factor and with ten times higher mass. A third component of higher density gas (>104 cm-3) is required to explain the mm-wave RRLs.
ISSN:0004-6361
1432-0746
1432-0756
DOI:10.1051/0004-6361:20041488